Distribution: South Africa. Western and Eastern Cape.Size to 57mm. 10-20m deep, in sheltered waters.

One distinctive feature is that rounded piral ridge that runs near the row of holes.This same ridge occurs in the Australian species H. scalaris (Leach, 1814).Dead collected, at 15m deep, on reef, False Bay, Western Cape. 33mm.

Same spot. 34mm. The surface is covered by quadrangular cells.

38mm specimen. The spiral ridge is clearly visible, even on ventral view.If colours and patterns are variable, the sculpture remains more or less constant.